Document processing systems optically read information from documents, which information may be stored if not used immediately for processing. Numerous systems may lift portions of the document in order to retain certain fields of information on the document, and the document may also be filmed with a microfilm camera at high speed to retain a copy of the entire document. To optically read and digitally store an image of a document generally requires a very large storage capacity with high speed document processors.
High speed processing of imaged data has principally included processing and compression of video data for use in facsimile transmission. In facsimile systems there is no need for long term storage of images as the document is reproduced as the information representative thereof is transmitted. In order to reduce the time to transmit such documents, various coding methods have been performed on the information. Such codes, referred to as run length coding, is used to compress the information; however, when it is desirable to run documents and capture images at rates up to 2000 documents per minute, it is necessary to temporarily store the information and rapidly code this information prior to storage on disks. Previously developed systems have not had sufficient capability for processing and storing images at such high speeds.
Image processing systems also require that the storage of the image be accomplished efficiently. Therefore, numerous data compression devices for compressing the original image pattern for storage and later retrieval by a decompression technique have been proposed. One such compression system is shown in U.S. Pat. No. 4,020,463 issued to D. P. Himmel on Apr. 26, 1977 and entitled "Apparatus and a Method for Storage and Retrieval of Image Patterns". A further data compressor system is shown in U.S. Pat. No. 4,145,686 issued to R. D. McMurray, et al. on Mar. 20, 1979 and entitled "Data Compressor". An apparatus utilizing a run length encoding method is shown in U.S. Pat. No. 3,502,806 issued to S. E. Townsend on Mar. 24, 1970 and entitled "Modified Run Length Data Reduction System".
Image processing systems also require the capability for diagnostic analysis of various portions or subsystems of the image processing system.
A need has thus arisen for a high speed image processing system which includes a video format unit for providing formatting of images for ultimate storage. In such a system, the images prior to being stored require video enhancement as well as compression to obtain optimum storage capability. A need has further arisen for an image processing system in which diagnostics on the video format unit can be effectively and efficiently accomplished.